Low-voltage lighting requires a transformer to step the line voltage (the voltage of the wiring without a transformer) down from 120V to 12V. They are popular because they are often smaller and more compact than other types of lamps, but you must locate the transformer or driver that powers them. They come in a wide variety of colors and beam spreads.
Popular low-voltage lamps include the MR16 and LEDs (light emitting diode).
Because of the transformer, they are usually more expensive than lighting which runs on line voltage, and they are not necessarily more energy efficient. LED low-voltage would be more efficient than halogen.
On the NCIDQ Practicum exam, you need to understand what lamps in the fixtures on the lighting cut sheets are low voltage because they require a low voltage dimmer $DLV.
